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Abstract

Tectaria fuscipes (Wall. ex Bedd.) C. Chr. (Baek-Rok-Go-Sa-Ri) is newly reported in Korea. This species belongs to the genus Tectaria Cav. of the family Tectariaceae Panigrahi. Thus far, no taxa of Tectariaceae have been reported in Korea. Tectaria fuscipes is characterized by its suberect to ascending rhizome, dimorphic or subdimorphic fronds, and free veins. The species was found on the southwestern slopes of Mt. Halla on Jeju Island, where it grows in sun near a small cave. It also occurs in southern China and in Taiwan. In Japan, eight species of the genus Tectaria have been reported, but T. fuscipes has yet to be recorded there. Jeju Island is the northeastern-most limit of the known range of this species.

Tectariaceae Panigrahi was accepted as an independent family in a revision of fern classification in 2006 (Panigrahi, 1986; Smith et al., 2006). The family Tectariaceae formed a large clade with Oleandraceae, Polypodiaceae, and Davalliaceae. It is the basal lineage among the four families of the clade (Smith et al., 2006). Tectariaceae has usually short-creeping to ascending rhizomes with scales. The fronds are monomorphic to strongly dimorphic. The blades are pinnate, bipinnate, or decompound. The rachis and costae are usually covered by articulate multicellular hairs. The indusia are reniform or peltate. The spores are of a brownish color and are monolete or monolete with various ornaments. (Smith et al., 2006; Sun et al., 2014). Within Tectariaceae, Tectaria is the largest genus and it is taxonomically confused (Cavanilles, 1799; Copeland, 1947). This genus contains 150–210 species that are mostly distributed in tropical areas (Tryon and Tryon, 1982; Holttum, 1991). Most members of the genus Tectaria have unlobed basal pinnae, but in some species the basal pinnae are lobed, in which case the basal basiscopic lobes or pinnule are the largest. The veins are copiously anastomosing, although some species have free veinlets (Sun et al., 2014). Since Tectaria has been generally accepted as a distinct genus (Underwood, 1906; Copeland, 1907; Ching, 1931; Christensen, 1934), its taxonomic delimitation has proved controversial (Ding et al., 2014). Molecular studies on plastid and nuclear markers of Tectaria strongly supported the monophyly (Ding et al., 2014; Zhang et al., 2016; Zhang et al., 2017). The most recent molecular data suggest that Tectaria is composed of four superclades and 12 major clades (Zhang et al., 2017).

Here, Tectaria fuscipes (Wall. ex Bedd.) C. Chr. of the family Tectariaceae is newly reported from Korea (Figs. 1, 2). The local name of the family and genus were given as “Mi-neul-chang-go-sa-ri” based on the English common name of “Halberd fern”. In botanical terminology, “Halberd” means arrowhead shaped with the basal lobes turned outward. Many Tectaria species have a halberd-shaped blade or pinna at the frond apex. “Halberd” is translated as “Mi-neul-chang” in Korean. “Mi-neul-chang” means a spear with two or three-pronged strands ending like branches and “Go-sa-ri” means fern. The Korean name of T. fuscipes, “Baek-rok-go-sa-ri”, means the white snow-covered slope where it was first discovered.

According to the molecular phylogeny of the genus Tectaria, T. fuscipes is included in the Ctenitopsis superclade and Ctenitopsis major clade (Zhang et al., 2017). Tectaria fuscipes has previously been treated as a synonym of T. paradoxa (Fée) Sledge (Sledge, 1972). On the other hand, Patil et al. (2014) distinguished T. fuscipes from T. paradoxa on account of its dimorphic fronds. However, partially monomorphic fronds were found in the population of Jeju Island, as in other studies (Wu et al., 2013; Sun et al., 2014) (Fig. 3). According to the frond type, T. fugipes of Jeju should be T. paradoxa, but the 13 commonly used morphological characters were all revealed as homoplastic in Tectaria in the recent phylogenetic studies (Ding et al., 2014; Zhang et al., 2017). This means that frond type is not a key character to distinguish T. fuscipes and T. paradoxa. The isotype specimen of Aspidium paradoxum (Herbier de l’Universite Montpellier II (MPU), MPU015614), which represents the basionym of T. paradoxa, differs morphologically from specimens of T. fuscipes collected on Jeju Island. Also, recent studies still maintain this synonymous name with insufficient information (Ding et al., 2014; Patil et al., 2014; Zhang et al., 2016; Zhang et al., 2017). Therefore, we use the name T. fugipes instead of T. paradoxa.

Several species of Tectaria have been reported from southern China (Guangxi, Guizhou, Hainan, Taiwan, Xizang, and Yunnan) and eight species have been reported in Japan (Iwatsuki et al., 1995; Wu et al., 2013). However, to date T. fuscipes has not been recorded in Japan. This species is also reported in India and most Southeast Asian countries: Cambodia, Indonesia, Myanmar, Nepal, Taiwan, Thailand, Vietnam (Ching, 1931; Holttum, 1988; Wu et al., 2013; Patil et al., 2014; Sun et al., 2014). In previous studies, the easternmost and northernmost distribution of the species was known to be Taiwan and Xizang, respectively. The new discovery on Jeju Island therefore represents a northeastern extension of its range, and suggests that T. fuscipes may occur in the southern part of Japan. Additionally, other species of Tectariaceae which are native to China, Japan, and Taiwan may yet be found in Korea. Tectaria fuscipes grows in full sun 3–4 m from the entrance of a small, humid cave. This cave is situated at 300–400 m above sea level on the southern slopes of Mt. Halla, and there is a distinct temperature difference across its entrance. This specific habitat is very limited, making T. fuscipes prone to disturbance and extirpation. Only ca. 50 individuals were seen in an area of approximately 3 m2. Careful research needs to be conducted to survey more suitable habitats of T. fuscipes and to conserve this rare species in Korea.

Taxonomic Treatment

Tectariaceae Panigrahi

Pantropical terrestrial herbs. Rhizome usually short-creeping to ascending, dictyostelic, bearing scales; petioles not abscising, with a ring of vascular bundles in cross-section; blades simple, pinnate, or bipinnate, sometimes decompound; indument of jointed, usually short stubby hairs on the axes, veins, and sometimes laminar tissue, especially on rachises and costae adaxially; veins free or often highly anastomosing, sometimes with included veinlets; indusia reniform or peltate (lost in several lineages); spores brownish, reniform, monolete, variously ornamented; x = 40 (a few genera with x = 41, some dysploids with x = 39).

Habitat:Tectaria fuscipes grows in sun close to the entrance of a cave. The cave has a lot of moisture and the width of the cave opening is about 3 m. Tectaria fuscipes grows with Arachniodes rhomboidea and Crepidomanes sp. The vegetation in the vicinity consists of coppiced Mallotus japonicus, Rosa multiflora, Smilax china, etc.

Acknowledgments

We would like to thank Dr. Stephan Gale (Kadoorie Farm and Botanic Garden) for the English proofreading of our manuscript. This research was supported by the BK21 Plus Program (Creative Academy of Eco Science, 31Z20130012990) funded by the Ministry of Education and National Research Foundation of Korea.

Zhang, L. Schuettpelz, E. Rothfels, CJ. Zhou, X-M. Gao, X-F and Zhang, L-B. 2016. Circumscription and phylogeny of the fern family Tectariaceae based on plastid and nuclear markers, with the description of two new genera: Draconopteris and Malaifilix (Tectariaceae). Taxon 65: 723-738.